The present invention relates to an electronically controlled magnetic tape editor for video tape recorder (VTR), of helical scan type, or the like.
The electronic editing technique of the VTR has been put into practical use many years ago. However, the recording density of the VTR has greatly improved over the years and the narrow track recording is executed, so that electronic editing accuracy has become a factor which limits the realization of increased high density recording.
One limit of the recording density which causes a problem in electronic editing relates to the linearity (defined by a degree of curve from a straight line) between the recording track pitch and the track.
At present, in the helical scan type VTR having a rotary head cylinder whose diameter is about 70 mm.phi., the limit of the track linearity is about 5.mu.m. When the linearity is set to about 5 .mu.m, assuming that the linearity between the recorded track and the editing track which is subsequently recorded shows an opposite curve, a deviation of the linearity at an editing point is equivalently set to 10 .mu.m. Therefore, to execute the electronic editing under such a condition without causing problems, it is desirable to set the track pitch to about 30 .mu.m or more.
On the other hand, due to recent technological advances with respect to magnetic tapes and heads, the recording and reproducing picture quality performances can be derived even in the case of a track pitch of 10 .mu.m or less. Further, there has also been known a dynamic tracking technique in which even when the recording track pitch is set to 10 .mu.m and the linearity of the recording track is set to 5 .mu.m, if each track has a curve of the same tendency, the reproduction is accurately executed along the recording track by the dynamic tracking which traces the curve in the reproducing mode.
However, in the case of performing electronic editing as mentioned above, when the video deck used to record first and the video deck which is used to execute the electronic editing differ, the track curves change discontinuously, particularly, at the positions before and after the editing point. Consequently, there occur phenomena such that the track overlap on the editing point track, the guard between tracks is widened, and the like. When reproducing the tape after the editing is completed, fluctuation of the reproduced image may occur. Effective means for avoiding such a problem in the case of the track pitch of about 20 .mu.m or less has not been heretofore practically achieved.